Gasification of organic matter is one possible way of recovering the energy therein, the other ways being combustion and ion methanisation.
The organic material is always constituted primarily of molecules composed of carbon C, hydrogen H and oxygen O, optionally combined with H2O water. If the organic material is subjected to a temperature of over 150° C. in an oxygen-deficient atmosphere, it then undergoes a transformation called pyrolysis, which breaks up the carbon molecules by breaking the covalent bonds. Products obtained during said pyrolysis are solids (mineral ash plus residual carbon called Char), vapours which condense at ambient temperature and pressure (tars, oils) and synthetic gas, called syngas, which remain in the gaseous state at ambient temperature and pressure (carbon monoxide, dihydrogen and gaseous elements that are of little economic value, such as carbon dioxide).
The char produced by pyrolysis also undergoes gasification by combination of carbon with oxygen, said oxygen partially coming from the molecules of the original organic material, and hydrogen which produces carbon monoxide, and dihydrogen methane in ideal conditions. This reaction is endothermic and requires a specific thermal input. Traditionally this contribution is provided by an air combustion reaction carried out in the method.
According to the current state of the art of organic matter gasification, syngas production uses two main technologies:                In a cocurrent or counter-current fixed bed process, with a so-called slow pyrolysis, the raw material is introduced into a chamber in which it undergoes the steps of pyrolysis and gasification during its displacement. Air is introduced locally in the chamber in order to enable partial combustion of the char and to generate the energy required for endothermic gasification. The gases produced are extracted from either the side of the entrance of the raw material (counter-current logic) or the side of the ash outlet (co-current logic).        In a fluidized bed of process with so-called fast pyrolysis, the raw material is first finely ground and then introduced into a reactor where a mass of hot particles, for example sand dolomite, is stirred. The raw material powder then almost instantly undergoes stages of pyrolysis and gasification. The gases produced were collected in a single main outlet placed in the upper position. The next step separates the gases produced with sand. It is then recirculated to the reactor to be recycled in the case of circulating fluidized beds.        
These traditional solutions in particular have the following defects:                In the case of the fluidized bed, the raw material must be carefully calibrated to be distributed quickly in the sand bed. To this end, a complex crushing apparatus and calibration of the incoming material is required. The sand bed is kept in a state of turbulence, which implies sand with perfect fluidity, and any ash melting primer within the sand bed strongly compromises the efficiency of the process. For these reasons, fluidized bed processes are operated at temperatures generally below 900° C., and the presence of alkali such as potassium must be very limited. Therefore, a temperature of 900° C. implies the residual presence of polycyclic aromatic hydrocarbons (tars) and does not ensure the complete gasification of the char.        
In the case of the fixed bed, the raw material descends by gravity while the gas must flow therein. It is necessary to avoid introducing particles that are too thin or small, typically less than 1 mm in diameter, as this could block the homogeneous flow of gas in the bed. The raw material is screened in order to reject fines before the introduction thereof into the pyrolysis reactor. Whatever the precautions taken, preferential currents are unavoidable with a bed collapse risk. For these reasons, co-current fixed beds are limited to low-power (less than 2 MW) and counter-current fixed beds do not enable use of the syngas in engines or turbines due to insufficient gas quality.                In both cases the reaction that occurs first is pyrolysis because the energy required for processing the raw material is supplied by combustion carried out in the same device so that heat is immediately available. The absence of such an arrangement is that the combustion generates the occurrence of undesirable elements such as nitrogen oxides which are then mixed with the syngas to the detriment of the quality thereof. Moreover, it is not possible to recover the thermal energy of the gas as it leaves the equipment to supply the gasification process, which leads to a yield loss that generally exceeds 10%.        
Previous solutions, which are currently seldom used, implement a raw material mixed in a fixed or rotating drum to ensure consistency and advancement of the products from an inlet to an outlet. Some mixing accessories are present in the device, but the failure of these solutions is that no specific mechanical action is planned during processing to facilitate the release of vapours during pyrolysis. In addition, the operating temperatures are generally below 600° C., not allowing the production of syngas of sufficiently high-quality for use in an engine or a turbine.